1. Technical Field of the Invention
This invention relates generally to digital memory such as used in computers, and more specifically to organization and design of memory modules such as DIMMs.
2. Background Art
Digital memories are utilized in a wide variety of electronic systems, such as personal computers, workstations, servers, consumer electronics, printers, televisions, and so forth. Digital memories are manufactured as monolithic integrated circuits (“ICs” or “chips”). Digital memories come in several types, such as dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, electrically erasable programmable read only memory (EEPROM), and so forth.
In some systems, the memory chips are coupled directly into the system such as by being soldered directly to the system's main motherboard. In other systems, groups of memory chips are first coupled into memory modules, such as dual in-line memory modules (DIMMs), which are in turn coupled into a system by means of slots, sockets, or other connectors. Some types of memory modules include not only the memory chips themselves, but also some additional logic which interfaces the memory chips to the system. This logic may perform a variety of low level functions, such as buffering or latching signals between the chips and the system, but it may also perform higher level functions, such as telling the system what are the characteristics of the memory chips. These characteristics may include, for example, memory capacity, speed, latency, interface protocol, and so forth.
Memory capacity requirements of such systems are increasing rapidly. However, other industry trends such as higher memory bus speeds, small form factor machines, etc. are reducing the number of memory module slots, sockets, connectors, etc. that are available in such systems. There is, therefore, pressure for manufacturers to use large capacity memory modules in such systems.
However, there is also an exponential relationship between a memory chip's capacity and its price. As a result, large capacity memory modules may be cost prohibitive in some systems.
What is needed, then, is an effective way to make use of low cost memory chips in manufacturing high capacity memory modules.